datatable.FExpr.alias()

datatable.FExpr.

alias

(

*names

)

source

Assign new names to the columns from the current FExpr.

Parameters

names

str | List[str] | Tuple[str]

New names that should be assigned to the columns from the current FExpr.

return

FExpr

New FExpr which sets new names on the current one.

Examples

Create a frame:

from datatable import dt, f, by DT = dt.Frame([[1, 2, 3], ["one", "two", "three"]]) DT

	C0	C1
	int32	str32
0	1	one
1	2	two
2	3	three

3 rows × 2 columns

Assign new names when selecting data from the frame:

DT[:, f[:].alias("numbers", "strings")]

	numbers	strings
	int32	str32
0	1	one
1	2	two
2	3	three

3 rows × 2 columns

Assign new name for the newly computed column only:

DT[:, [f[:], (f[0] * f[0]).alias("numbers_squared")]]

	C0	C1	numbers_squared
	int32	str32	int32
0	1	one	1
1	2	two	4
2	3	three	9

3 rows × 3 columns

Assign new name for the group by column:

DT[:, f[1], by(f[0].alias("numbers"))]

	numbers	C1
	int32	str32
0	1	one
1	2	two
2	3	three

3 rows × 2 columns